1. Field of the Invention
This invention pertains to a method and apparatus for mining and more particularly to a method for dislodging material from a mine face under an advancing temporary mine support.
2. Description of the Prior Art
In the past the material has been removed from a mine by placing a mining apparatus in the vicinity of the mine face and removing material from the mine face to a depth of approximately ten to twenty feet. The miner is then removed from the mine face and a roof support system is installed in the excavated portion of the mine. After a roof support system has been installed, the miner is then brought back to the mine face and the mining operation continued. The removing and bring back of the miner to the mine face is a cumbersome and time consuming operation often causing damage to the equipment. A more efficient mining operation has been sought.
In U.S. Pat. No. 3,995,905, an apparatus is disclosed which attempts to avoid this problem. A series of roof beam supports are hydraulically raised from a mining apparatus which temporarily supports the roof as material is dislodged from the mine face. Roof bolts are installed at the rear section of the temporary roof supports. When the miner is to be advanced, the series of temporary roof supports are lowered and the miner is advanced. After the miner has advanced, the series of temporary roof supports are lifted and resupport the roof. The roof of the mine, however, is subjected to the cycle of support, nonsupport and resupport. This cycling of the mine roof is detrimental to the structure of the mine roof causing weakness of the roof.
The apparatus, furthermore, requires an extensive amount of hydraulic lifting equipment making the apparatus cumbersome, difficult to maneauver and prone to mechanical failure.
More recently in U.S. Pat. No. 4,143,991 an apparatus is described for providing a temporary support system over the miner which is not attached to the miner. This Patent, however, as with the above mentioned U.S. Pat. No. 3,995,905, is also cumbersome and has the undesirable affect of cycling the roof.
A simplified means for providing a temporary roof support system which does not cycle the roof has been sought.